Jennifer Hale, who voices Fem-Shep, recently told Edge she has yet to be contacted by BioWare about recording any new lines.

From the Edge piece:

She hasn't been contacted by the team, hasn't had a recording session, or been given any indication that she will be needed for this new content.

What this means for the ME3: Extended Cut content is unclear. What we do know is that the new (free) content will provide "additional cinematic sequences and epilogue scenes" to the ending, and it'll launch this summer.

The Extended Cut is designed to give players "deeper insights into how their personal journey concludes", as per BioWare.

As for some quotes from Ms. Hale on the subject of ME3's upcoming epilogue, she said, "I have mixed feelings about [the prospect of a new ending]. I really respect the team and what they did and how hard they worked. And endings are hard! They're cutting new ground; the players are so involved in this game that to come up with an ending to something everyone's got their hand in is a huge challenge.

"So maybe it's going to take a little work to get everything sorted in a way that's going to make everybody happy."